Thanks for your reading.
I made the sub program which defines the mathematical function with notebook form. (Let its name be filename.nb, which is in the same folder as the main program.) But inputting command
Import["" \\ filename.nb ""]
imports the filename.nb, but does not execute it automatically. So, now I have to first input
Import["" \\ func - taylorn.nb ""] on the main window, and next, execute the filename.nb on the other window, and finally execute the rest part of the main program on the main window.

I would like to know whether there are methods of executing only main program without opening the window of filename.nb separately.